1. Field of the Invention
The present invention relates to a positioning device for bone drilling, and more particularly to a positioning device for bone drilling or implantation.
2. Description of Related Art
In a conventional surgery method, a doctor plans the position and path of inversion according to an X-ray image or a computerized tomography of a patient's bone, as well as relying on the doctor's anatomy knowledge and clinical surgery experience. As accuracy, safety and reliability of a surgery rely crucially on the clinical experience of the doctor, a less experienced doctor may not be able to fully control the quality of surgery. Selection of position and angle of a bone screw implant is crucial so as to avoid hurting a nerve and a vein of a patient during a surgery, otherwise the patient may suffer from sequelae such as hemiplegia.
For a dentist, when a patient's tooth is broken or missing, a normal treatment is to replace the tooth with a denture. A common method of a denture implant is fixed tooth implant. The fixed tooth implant is drilling a hole at an appropriate position where a tooth is missing on a gum bone in a patient's mouth, and then an artificial tooth root is implanted in the hole. The hole is sutured after implantation of the artificial tooth root. When the artificial tooth root grows fully integrated with the gum bone, a holder having a screw is mounted on the artificial tooth root. The denture is mounted around the holder and fully sustained on the gum bone by the holder and the artificial tooth root, so the denture can bear a bite force between the upper and down rows of teeth of the patient to restore a biting function of the patient's teeth.
Furthermore, depth, angle, position and size of the hole on the gum bone of the patient influence afterwards the depth and position of the implantation of the artificial tooth root on the gum bone of the patient, and even influence the biting between the denture and the patient's original teeth. In addition, a dentist must first drill a small hole on the gum bone of the patient, and then gradually enlarge the hole to prevent the gum bone of the patient from collapsing during drilling due to osteoporosis.
U.S. Pat. No. 7,322,821, which is incorporated herein as a reference, discloses a conventional positioning device for bone drilling and has a magnetic rod. An outer side of the magnetic rod attracts multiple semicircular guiding panels into stack by a magnetic force. A radius of curvature of each semicircular guiding panel gradually increases from the innermost guiding panel attached on the magnetic rod to the outermost guiding panel.
A dentist can simulate an angle and a diameter of the hole drilled on the position of the missing tooth on the gum bone of the patient by the conventional positioning devices based on a model of a gum of the patient, and accordingly make a guide mold mounted around the position of the missing tooth on the gum bone of the patient. The guide mold has a notch corresponding to the missing tooth in position to accommodate the conventional positioning devices. Drilling the hole on the gum bone of the patient includes the following steps.
First, the magnetic rod is removed, and then the dentist drills the hole with a drill having a rod diameter that equals the radius of curvature of the innermost guiding panel to drill downward on the position of the missing tooth on the gum bone of the patient through a preset angle of the innermost guiding panel.
Second, the innermost guiding panel is removed, and then the dentist drills the hole with a drill having a rod diameter that equals the radius of curvature of the next guiding panel to drill downward and enlarge the hole on the position of the missing tooth on the gum bone of the patient.
The dentist removes the guiding panels in sequence and uses the drills having different rod diameters to gradually enlarge the hole on the gum bone of the patient as desired.
However, the conventional positioning devices are simply placed in the notch of the guide mold without any design or mechanism to be fixed on the guide mold, so relative displacement between the conventional positioning devices and the guide mold frequently occurs. Consequently, the dentist cannot drill the hole at the accurate position, at the accurate oblique angle, and in the accurate direction as preset. In another aspect, the conventional positioning devices can be fixed by a fixing hole drilled on the magnetic rod and the guiding panels with a fixing part protruding into the fixing hole to fix a relative position between the magnetic rod and the guiding panels. However, when drilling a hole on a gum bone, sizes of the magnetic rod and the guiding panels are almost as large as a tooth, and the magnetic rod and the guiding panels thus have to be compactly designed. If the conventional positioning devices further include the fixing hole and the fixing part protruding in the fixing hole, a manufacture of the conventional positioning devices becomes highly complicated. Therefore, the conventional positioning devices still have to be improved.